Earthfall: Homecoming: Volume 4 (Homecoming Saga, 4)

High above the planet Harmony, the Oversoul watches, programmed forty million years ago to guard the human settlement from all threats, especially themselves. In the latest in the Hugo- and Nebula award-winning author's Homecoming series, the great artificial intelligence has lost control of the population, forbidden technology has been rediscovered, war has broken out, and the only repair lies light years distant on a lost and ruined Earth.

"There seems little doubt that the whole series will prove as readable--and as morally committed--as we've come to expect from Card." --Locus